In the punch and die art and particularly in the field of high-speed automated forming and punching equipment for punching and forming workpiece, e.g., sheet metal and especially in the case of automated turret punch presses, the punch presses are operated by computer to rapidly perform a series of punching or forming operations sequentially. These punch presses which by themselves form no part of the present invention are typically provided with aligned upper and lower turrets that rotate and are indexed intermittently between punching operations. The turrets may hold as many as a dozen or more separate punches that are used in sequence for performing given operations. A multiple punch or “multi-punch” has several punches in a single casing or assembly. When a punch is struck from above by the punch press ram, a single selected punch element or punch insert within the assembly is driven downwardly through the workpiece to perform the punching operation, while the other punches (those not selected) remain inactive. When released, the punch insert is retracted by a spring provided in the punch assembly.
Prior multi-punches exhibit certain shortcomings. Some are not suited for standard tooling used for single station punches since they required stations of special construction or special tooling that cannot be used in standard equipment such as the well-known “thick turret” style tooling. Another shortcoming is the time, effort, and inconvenience involved in disassembling a punch assembly because of the need for hand tools required to take them apart. Thus, in multi-punches now in use such as those shown, for example, in U.S. Pat. Nos. 6,675,688 and 7,032,812, the strikers, gears, and connected components all have to be removed with wrenches or other tools in order to remove, adjust, or replace punches or worn internal parts. In addition, vibration or impact shock will occasionally jar one or more of the unused punches causing it to be elevated enough above its normal resting position to strike the punch ram as punch assemblies are rapidly indexed from one position to another during operation. When this happens, it can, of course, severely damage the punch or other parts of the equipment. The Matrix company of Schio Italy makes a thick turret punch such as a ½″ station punch with no center shaft, but occasionally one of the inactive punches can be jarred enough to bounce upwardly a fraction of an inch as the punches are rapidly switched between stations under the control of the punch press computer and when elevated in this way, the punch can accidentally strike the ram causing damage to the machine. Thus, there is no positive way of preventing damage from parts accidentally striking one another during operation. A still further disadvantage of prior multi-punches is the tendency for one or more of the unused punches to mark or otherwise score the top of the workpiece as the active punch is driven through the workpiece. Die carriers are also subject to stress cracking.
In view of these and other deficiencies of the prior art, it is one object of the present invention to provide an improved multi-punch and die assembly suited for wide application in a variety of presses using standard tooling including “thick turret” style tooling rather than being limited for use in a special tooling set-up.
Another object of the invention is to provide an improved multiple punch and die assembly that makes possible hand disassembly and punch length adjustment, i.e. servicing, adjustment, and punch replacement without the use of tools.
Another object of the invention is to prevent damage to inactive punches or associated equipment as the punch assembly is rapidly indexed between successive operating positions.
Yet another object of the invention is to prevent inactive punches from striking, scoring, or otherwise marking a workpiece the active punch is driven through the workpiece.
Still another object of the invention is to reduce or eliminate stress on the die carrier due to repeated impact forces as the punches are driven through a die.
These and other more detailed and specific objects of the present invention will be better understood by reference to the following Figures and detailed description which illustrate by way of example but a few of the various forms of the invention within the scope of the appended claims.